Apparatus and method for selectively treating a surface of a component

ABSTRACT

An anodising apparatus for selectively anodizing at least a portion of a surface of a component can include a conformable wicking element configured to absorb a fluid, the conformable wicking element being conformable to at least the portion of the surface of the component, wherein, upon bringing the component into contact with the conformable wicking element, the fluid completes an electric circuit between the component and a conductive element, the anodising apparatus being configured to grow an anodised layer on the portion of the surface of the component that is in contact with the conformable wicking element when an electric current is supplied to the electric circuit between the conductive element and the component.

The present disclosure relates to apparatus and a method for selectivelytreating at least a portion of a surface of a component, and inparticular, but not exclusively, relates to selectively anodising asurface of a component using surface treatment apparatus comprising aconformable wicking element.

PRIORITY APPLICATION

This application claims the benefit of priority under 35 U.S.C. 119 toUnited Kingdom Application No. 1503437.4 filed on Feb. 27, 2015 whichapplication is incorporated herein by reference in its entirety.

BACKGROUND

During a surgical procedure, for example a hip arthroplasty, a surgeonmay be provided with a set of differently sized prostheses from whichthe most suitable prosthesis may be chosen in accordance with theanatomy of the patient. A net of surgical instruments, for example trialimplants, may be used whilst performing the surgical procedure to assesswhich size of prosthesis best matches the patient's anatomy. Each trialimplant may have differently sized features that correspond to thedifferently sized prostheses. It is desirable, therefore, during surgeryto be able to easily match the prosthesis and the corresponding trialimplant.

It is known to colour-code components using anodisation techniques tohelp identify prostheses and tools. Such anodisation techniquestypically involve immersing the component in acid to remove an oxidelayer, and subsequently performing the anodisation by submerging thecomponent an electrolyte fluid. However, it is very difficult toselectively anodise a specific surface of the component using such knowntechniques. Even if the component is partially immersed in the fluid totreat only a specific portion of the component, the surface tension ofthe fluid results in unwanted treatment of the component where thecomponent breaks the surface of the fluid. It is desirable, therefore toselectively anodise only the specific surface of the component to avoidintroducing any unwanted chemicals onto other surfaces of the component,for example surfaces of a prosthesis designed to engage a bone and/oranother prosthetic component, and to avoid any unsightly anodisationgradients between treated surfaces and the surfaces adjoining thetreated surfaces.

Overview

According to an aspect of the present disclosure there is providedanodising apparatus for selectively anodizing at least a portion of asurface of a component. The anodising apparatus comprises a conformablewicking element configured to absorb a fluid. The conformable wickingelement is conformable to at least the said portion of the surface ofthe component. The fluid completes an electric circuit between thecomponent and a conductive element upon bringing the component intocontact with the conformable wicking element. The anodising apparatus isconfigured to grow an anodised layer on the said portion of the surfaceof the component that is in contact with the conformable wicking elementwhen an electric current is supplied to the electric circuit between theconductive element and the component.

The fluid may be exposed to only the said portion of the surface of thecomponent upon bringing the component into contact with the conformablewicking element. The conformable wicking element may be configured toabsorb, for example draw, the fluid from a reservoir of fluid, forexample by capillary action. The conformable wicking element may be atleast partially submerged in the fluid. The conformable wicking elementmay be fabricated from a porous material. The conformable wickingelement may a comprise a sheet of porous material. The conformablewicking element may be fabricated from a resilient material. Theconformable wicking element may be in contact with the conductiveelement and the said portion of the surface of the component. Theconformable wicking element may be configured to at least partiallycover one or more surfaces of the conductive element. The conformablewicking element may be at least partially disposed in between thecomponent and the conductive element. The conformable wicking elementmay be conformable to at least a portion of a surface of the conductiveelement.

The conductive element may comprise a planar surface at least partiallyin contact the conformable wicking element. The conductive element maycomprise a surface having at least a portion that is of similar form tothe said portion of the surface of the component. The conductive elementmay be configured to support the conformable wicking element. Theconductive element may bead least partially submerged in the fluid. Theconductive element may comprise a metallic plate. The conductive elementmay comprise one or more grooves running at least partially across asurface of the conductive element. The grooves may be configured toallow the fluid to flow at least partially across a surface of theconductive element. The grooves may extend at least partially across asurface of the conductive element from the periphery of the conductiveelement. The grooves may form a grid pattern on a surface of theconductive element. The grooves may be configured to drain fluid awayfrom the conformable wicking element.

The conductive element may comprise a porous conductive materialconfigured to absorb the fluid. The conductive element may comprise afirst layer of a non-porous conductive material and a second layer ofporous conductive material configured to absorb the fluid.

The anodising apparatus may comprise a second wicking element configuredto absorb the fluid. The second wicking element may be in contact withthe conformable wicking element. The conformable wicking element may beconfigured to draw the fluid from the second wicking element. The secondwicking element may be at least partially disposed in between theconformable wicking element and the conductive element.

The fluid may comprise an electrolyte fluid. The fluid may comprise acleaning fluid, for example a fluid configured to remove an oxide layerfrom the component.

The conformable wicking element may be remote from the conductiveelement. The fluid may connect electrically the conductive element tothe conformable wicking element. The fluid may connect electrically theconductive element to the component.

The conformable wicking element may be supported by a non-conductivecarrier member. The porosity of conformable wicking element may beselectable depending on a required flow rate of the fluid into, out ofand/or through the conformable wicking element. The conformable wickingelement may have a uniform thickness. The conformable wicking elementmay have a varying thickness. The conformable wicking element maycomprise one or more raised surfaces configured to support thecomponent.

The conductive element may form a cathode of the anodising apparatus.The component may form an anode of the anodising apparatus.

The anodising apparatus may comprise a pump configured to pump thefluid, for example towards and/or away from the conformable wickingelement. The anodizing apparatus may comprise a rotational driveconfigured to rotate the component and/or one or more components of theanodising apparatus, for example the conductive element and/or theconformable wicking element. The anodising apparatus may comprise anactuator, for example a linear actuator, configured to move, for exampletranslate, the component and/or one or more components of the anodisingapparatus, for example the conductive element and/or the conformablewicking element. The anodising apparatus may comprise a vibrating deviceconfigured to vibrate the component and/or one or more components of theanodising apparatus, for example the conductive element and/or theconformable wicking element. The anodizing apparatus may comprise aloading device configured to adjust the contact pressure between thecomponent and the conformable wicking element.

The anodising apparatus may comprise a controller configured to adjustthe electric current applied between the component and the conductiveelement. The controller may be configured to modulate an alternatingcurrent supply applied between the component and the conductive element.The controller may be configured to control one or more of: therotational drive; the linear actuator; the vibrating device; the loadingdevice; and the pump.

The component may be a prosthesis, for example an acetabular cup. Thecomponent may be a tool, for example a reaming tool, for use during asurgical procedure.

The conformable wicking element may be remote from the conductiveelement. The fluid may connect electrically the conductive element tothe conformable wicking element. The fluid may connect electrically theconductive element to the component.

According to another aspect of the present invention there is provided amethod of selectively anodizing at least a portion of a surface of acomponent using anodizing apparatus. The anodising apparatus comprises aconformable wicking element conformable to at least the portion of thesurface of the component. The conformable wicking element is configuredto absorb an fluid. The fluid completes an electric circuit between thecomponent and a conductive element. The method comprises priming theconformable wicking element with the fluid. The method comprisesbringing the component into contact with the conformable wicking elementto complete the electric circuit between the component and theconductive element. The method comprises applying an electric currentbetween the conductive element and the component to grow an anodisedlayer on the portion of the surface of the component that is in contactwith the conformable wicking element.

The method may comprise rotating the component and/or one or morecomponents of the anodising apparatus using a rotational drive. Themethod may comprise rotating the component relative to one or morecomponents of the anodising apparatus, for example the conformablewicking element, using a rotational drive. The method may comprisemoving the component and/or one or more components of the anodisingapparatus using an actuator, for example a linear actuator. The methodmay comprise moving the component relative to one or more components ofthe anodising apparatus, for example the conformable wicking element,using an actuator.

The method may comprise vibrating the component and/or one or morecomponents of the anodising apparatus using a vibrating device.

The method may comprise adjusting the contact pressure between thecomponent and the conformable wicking element using a loading device.The loading device may be configured to increase and/or decrease thecontact pressure depending on the requirements of the anodising process.For example, if the surface portion to be anodised is small and/or ifthe component is heavy, the contact pressure between the component andthe conformable wicking element will be high, and the loading device maybe configured to reduce the contact pressure. Conversely, if the surfaceportion to be anodised is large and/or if the component is light, thecontact pressure between the component and the conformable wickingelement will be low, and the loading device may be configured toincrease the contact pressure.

The method may comprise controlling, for example adjusting, the electriccurrent supplied to the electric circuit using a controller. Forexample, the controller may be configured to modulate an alternatingcurrent (AC) supply. The controller may be configured to control atleast one of the rotational movement and/or linear movement of thecomponent and/or one or more components of the anodising apparatus, forexample the conductive element and/or the conformable wicking element.

According to another aspect of the present invention there is provided asurface treatment apparatus for selectively treating at least a portionof a surface of a component. The surface treatment apparatus comprises aconformable wicking element configured to absorb a fluid. Theconformable wicking element is conformable to at least the said portionof the surface of the component. The surface treatment apparatus isconfigured to expose only the said portion of the surface of thecomponent to the fluid.

The surface treatment apparatus may further comprise a second wickingelement configured to absorb the fluid. The second wicking element maybe in contact with the conformable wicking element. The conformablewicking element may be configured to draw the fluid from the secondwicking element.

The fluid may be exposed to the said portion of the surface of thecomponent upon bringing the component into contact with the conformablewicking element.

The conformable wicking element and/or the second wicking element may beconfigured to absorb, for example draw, the fluid from a reservoir offluid. The conformable wicking element and/or the second wicking elementmay be at least partially submerged in the fluid. The conformablewicking element and/or the second wicking element may comprise one ormore sheets of porous material.

The surface treatment apparatus may be configured to clean the saidportion of the surface of the component that is in contact with theconformable wicking element. The fluid may comprise a cleaning fluid,for example an acid configured to remove a layer of metal oxide from thesurface of a metal component.

The fluid may complete an electric circuit between the component and aconductive element upon bringing the component into contact with theconformable wicking element.

The surface treatment apparatus may be configured to grow an anodisedlayer on the said portion of the surface of the component that is incontact with the conformable wicking element upon supplying an electriccurrent to the electric circuit between the conductive element and thecomponent.

The conformable wicking element may be in contact with the conductiveelement and the said portion of the surface of the component. Theconformable wicking element may be at least partially disposed inbetween the component and the conductive element. The conformablewicking element may be configured to at least partially cover one ormore surfaces of the conductive element. The conformable wicking elementmay be conformable to at least a portion of a surface of the conductiveelement.

The conductive element may comprise a planar surface at least partiallyin contact the conformable wicking element. The conductive element maycomprise a surface having at least a portion that is of similar form tothe said portion of the surface of the component. The conductive elementmay be configured to support the conformable wicking element. Theconductive element may be at least partially submerged in the fluid. Theconductive element may comprise a metallic plate. The conductive elementmay comprise one or more grooves running at least partially across asurface of the conductive element. The grooves may be configured toallow the fluid to flow at least partially across a surface of theconductive element. The grooves may extend at least partially across asurface of the conductive element from the periphery of the conductiveelement. The grooves may form a grid pattern on a surface of theconductive element. The grooves may be configured to drain fluid awayfrom the conformable wicking element.

The conductive element may comprise a porous conductive materialconfigured to absorb the fluid. The conductive element may comprise afirst layer of a non-porous conductive material and a second layer ofporous conductive material configured to absorb the fluid.

The conformable wicking element may be supported by a non-conductivecarrier member. The porosity of conformable wicking element may beselectable depending on required flow rate of the fluid into, out of orthrough the conformable wicking element. The conformable wicking elementmay have a uniform thickness. The conformable wicking element may have avarying thickness. The conformable wicking element may comprise one ormore raised surfaces configured to support the component.

The conductive element may form a cathode of the anodising apparatus.The component may form an anode of the anodising apparatus.

The surface treatment apparatus may comprise a pump configured to pumpthe fluid, for example towards and/or away from the conformable wickingelement. The anodising apparatus may comprise a rotational driveconfigured to rotate the component and/or one or more components of theanodising apparatus, for example the conductive element and/or theconformable wicking element. The anodising apparatus may comprise anactuator, for example a linear actuator, configured to move, for exampletranslate, the component and/or one or more components of the anodisingapparatus, for example the conductive element and/or the conformablewicking element. The anodising apparatus may comprise a vibrating deviceconfigured to vibrate the component and/or one or more components of theanodising apparatus, for example the conductive element and/or theconformable wicking element. The anodising apparatus may comprise aloading device configured to adjust the contact pressure between thecomponent and the conformable wicking element.

The surface treatment apparatus may comprise a controller configured toadjust the electric current applied between the component and theconductive element. The controller may be configured to modulate analternating current supply applied between the component and theconductive element. The controller may be configured to control one ormore of: the rotational drive; the linear actuator; the vibratingdevice; the loading device; and the pump.

The component may be a prosthesis, for example an acetabular cup. Thecomponent may be a tool, for example a reaming tool, for use during asurgical procedure.

The component may be a prosthesis, for example an acetabular cup. Thecomponent may be a tool, for example a tool, e.g. a reaming tool, foruse during a surgical procedure.

The conformable wicking element may be remote from the conductiveelement. The fluid may electrically connect the conductive element tothe conformable wicking element. The fluid may electrically connect theconductive element to the component.

According to another aspect of the present invention there is provided amethod of selectively treating at least a portion of a surface of acomponent using surface treatment apparatus. The surface treatmentapparatus comprises a conformable wicking element configured to absorb afluid. The conformable wicking element is conformable to at least thesaid portion of the surface of the component. The surface treatmentapparatus is configured to expose only the said portion of the surfaceof the component to the fluid. The method comprises priming theconformable wicking element with the fluid. The method comprisesbringing the component into contact with the conformable wicking elementto expose only the said portion of the surface of the component to thefluid. The method comprises treating the said portion of the surface ofthe component that is in contact with the conformable wicking element.

According to another aspect of the present invention there is provided asurface cleaning apparatus for selectively cleaning at least a portionof a surface of a component. The surface cleaning apparatus comprises afirst wicking element configured to absorb a cleaning fluid. The surfacecleaning apparatus comprises a conformable second wicking element incontact with the first wicking element. The conformable wicking elementis conformable to at least the said portion of the surface of thecomponent. The conformable wicking element is configured to draw thecleaning fluid from the first wicking element. The cleaning fluid isexposed to the said portion of the surface of the component uponbringing the component into contact with the conformable wickingelement. The surface cleaning apparatus is configured to clean the saidportion of the surface of the component that is in contact with theconformable wicking element. The surface cleaning apparatus may be usedto clean the said portion of the surface of the component prior to usingthe above-mentioned anodising apparatus to anodise the said surface ofthe component. The surface cleaning apparatus may be used to clean ananodised portion of the surface of the component.

According to another aspect of the present invention there is provided amethod of selectively cleaning at least a portion of a surface of acomponent using a surface cleaning apparatus. The surface cleaningapparatus comprises a first wicking element configured to absorb acleaning fluid. The surface cleaning apparatus comprises a conformablesecond wicking element in contact with the first wicking element. Theconformable wicking element is conformable to at least the said portionof the surface of the component. The conformable wicking element isconfigured to draw the cleaning fluid from the first wicking element.The method comprises priming the first wicking element with the cleaningfluid. The method comprises bringing the component into contact with theconformable wicking element to expose the said portion of the surface ofthe component to the cleaning fluid. The method comprises cleaning thesaid portion of the surface of the component that is in contact with theconformable wicking element.

According to another aspect of the present invention there is providedsurface treatment apparatus for selectively cleaning and selectivelyanodizing at least a portion of a surface of a component. The surfacetreatment apparatus comprises a first surface treatment apparatus, forexample a surface cleaning apparatus, and a second surface treatmentapparatus, for example an anodising apparatus.

The first surface treatment apparatus comprises a first wicking elementconfigured to absorb a cleaning fluid. The first surface treatmentapparatus comprises a conformable second wicking element in contact withthe first wicking element. The conformable second wicking element isconformable to at least the said portion of the surface of thecomponent. The conformable second wicking element is configured to drawthe cleaning fluid from the first wicking element. The cleaning fluid isexposed to the said portion of the surface of the component uponbringing the component into contact with the conformable second wickingelement. The first surface treatment apparatus is configured to cleanthe said portion of the surface of the component that is in contact withthe conformable second wicking element.

The second surface treatment apparatus comprises a conformable thirdwicking element conformable to at least the said portion of the surfaceof the component. The conformable wicking element is configured toabsorb an electrolyte fluid. The electrolyte fluid completing anelectric circuit between the component and a conductive element uponbringing the component into contact with the conformable third wickingelement. The second surface treatment apparatus is configured to grow ananodised layer on the portion of the surface of the component that is incontact with the conformable third wicking element upon applying anelectric current between the conductive element and the component.

According to another aspect of the present invention there is provided amethod of selectively cleaning and selectively anodizing at least aportion of a surface of a component. The method comprises cleaning atleast the said portion of the surface of the component using a firstsurface treatment apparatus, for example a surface cleaning apparatus,and subsequently anodising at least the said portion of the surface ofthe component using a second surface treatment apparatus, for example ananodising apparatus.

The surface treatment apparatus and methods disclosed herein are notspecific to the treatment, for example the cleaning and/or anodisation,a prosthesis. It is appreciated that the surface treatment apparatus andmethods disclosed herein may be used in any other sector, for examplethe automotive industry.

To avoid unnecessary duplication of effort and repetition of text in thespecification, certain features are described in relation to only one orseveral aspects or embodiments of the invention. However, it is to beunderstood that, where it is technically possible, features described inrelation to any aspect or embodiment of the invention may also be usedwith any other aspect or embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present disclosure, and to show moreclearly how it may be carried into effect, reference will now be made,by way of example, to the accompanying drawings, in which:

FIG. 1a shows surface treatment apparatus configured to grow an anodisedlayer on at least a portion of a component;

FIG. 1b shows surface treatment apparatus configured to grow an anodisedlayer on at least the said portion of the component; and

FIG. 2 shows surface treatment apparatus configured to clean at least aportion of a component.

DETAILED DESCRIPTION

FIGS. 1a and 1b show surface treatment apparatus 101 for selectivelytreating, e,g. anodising apparatus for selectively anodising, at least aportion 103 of a surface of a component 105. In the example of FIGS. 1aand 1 b, the component 105 comprises a prosthesis, for example anacetabular cup. It is appreciated, however, that the surface treatmentapparatus 101 may be used to treat any appropriate component and/ortool, for example a component and/or tool used in the automotiveindustry.

In the example of FIGS. 1a and 1 b, the surface treatment apparatus 101comprises a conformable wicking element 107 and a conductive element 117disposed in a fluid reservoir 111 containing a fluid 113. The fluid 113may comprise an electrolyte fluid, for example sodium carbonatesolution, sulphuric acid, phosphoric acid, or any other fluid suitablefor use in an anodisation process. The conductive element 117 issubmerged in the fluid 113 and is configured to support the conformablewicking element 107 such that the conformable wicking element 107 ispartially submerged in the fluid 113. The conformable wicking element107 is configured to absorb the fluid 113, for example by virtue ofcapillary action, directly from the fluid reservoir 111. In this manner,the conformable wicking element 107 is primed with the fluid 113.

The conformable wicking element 107 may be fabricated from a porouswicking material configured to absorb the fluid 113 by capillary action.The pore size of the porous wicking material may be selected accordingto the desired rate of absorption of the fluid 113. The selection of thecharacteristics of the porous wicking material is key to enabling ananodisation process, particular, the pore size must be selected to allowthe conformable wicking element 107 to hold an appropriate amount ofelectrolyte fluid. If the pore size is too large, too much fluid iswicked and the conformable wicking element 107 may become saturated. Ifthe pore size is too small blockage of the pores may occur as a resultof deposition of a salt of the electrolyte fluid, for example a sodiumcarbonate salt. In one example, the porous material may have a pore sizebetween approximately 5 μm (micrometres) and 100 μm, for example thepore size may be approximately 35 μm. In the example of FIGS. 1a and 1bthe conformable wicking element 107 comprises a fibrous paper, althoughvarious other wicking materials may be used, for example a resilientopen-cell foam. In another example, the conductive element 117 maycomprise a porous conductive material configured to absorb the fluid113, for example a carbon doped porous polyethylene, a conductiveneoprene and/or an open-cell conductive rubber, that allows bothelectrical conduction and wicking of the fluid. In a further example,the conductive element 117 may comprise a sandwich construction having aplurality of layers, for example a first layer of a non-porousconductive material and a second layer of porous material configured toabsorb the fluid 113.

The conformable wicking element 107 is conformable to at least the saidportion 103 of the surface of the component 105 such that, upon bringingthe component 105 into contact with the conformable wicking element 107,only the said portion 103 of the surface of the component 105 is exposedto the fluid 113 held by the conformable wicking element 107. FIG. 1bshows the component 105, for example an acetabular cup, in contact withthe conformable wicking element 107. In the example of FIG. 1b only therim of the acetabular cup is in contact with the conformable wickingelement 107. In this manner, the surface treatment apparatus 101 isconfigured to treat only a selected surface of component 105.

The material from which the conformable wicking element 107 isfabricated is selected to ensure congruent contact between the saidportion 103 of the surface of the component 105 and the conformablewicking element 107. The conformable wicking element 107 may beconfigured to deform upon bringing the component 105 into contact withthe conformable wicking element 107. In this manner, the surfacetreatment apparatus 101 is configured to ensure that the fluid 113 isevenly exposed to only the said portion 103 of the surface to betreated. The surface treatment apparatus 101 is configured to ensurethat the fluid 113 is not exposed to any other surface of the component,for example one or more portions 115 of a surface that adjoins and/or is30 proximate to the said portion 103 of the surface to be treated.

The surface treatment apparatus 101 comprises an electric circuit 119connected between the component 105 and the conductive element 119. Whenthe component 105 is in contact with conformable wicking element 107,the fluid 113 absorbed into the conformable wicking element 107completes the electric circuit 119.

The surface treatment apparatus 101 is configured to grow an anodisedlayer on the said surface portion 103 that is in contact with theconformable wicking element 107 when an electric current is applied tothe electric circuit 119. Since the fluid 113 is exposed only to thesaid portion 103 of the surface of the component 105, the surfacetreatment apparatus 101 according to the present disclosure mitigatesgrowing an anodised layer on any surface, or portions 115 of anysurface, other than the said surface portion 103. The present disclosuretherefore ensures the controlled treatment of one or more selectedportions 103 of the surface of the component 105. In certain examples,the surface portions 115 that adjoin and/or are proximate to the saidsurface portion 103 may comprise other surface coatings, for example aporous hydroxyapatite coating. The surface treatment apparatus 101according to the present disclosure is beneficial as it is possible toavoid the chemical entrapment of any unwanted metal oxides into thosesurface portions 115. In other examples, the surface portions 115 thatadjoin and/or are proximate to the said surface portion 103 may havebeen precision manufactured within exact tolerances. As such, it isundesirable to introduce any unwanted surface treatments that may alterthe dimension and/or form of the surface portions 115. This inparticularly important where the surface portion 115 is a bearingsurface that engages a corresponding bearing surface on anothercomponent in use. The present disclosure therefore allows for theselective anodisation of one or more surfaces without the risk ofchanging the surface characteristics of any other surface of thecomponent.

The anodized layer is grown on the surface portion 103 by passing acurrent through the electrolyte fluid 113. When the component 105 isbrought into contact with the surface treatment apparatus 101, thecomponent 105 serves as an anode and the conductive element 117 servesas a cathode.

When the current is supplied to the electric circuit 119, hydrogen isreleased at the cathode, i.e. the conductive element 117, and oxygen isreleased at the surface of the anode, the component 105, which creates abuild-up of metal oxide on the surface portion 103.

For the example of the acetabular cup, it is possible to utilise anexisting feature of the component, e.g. a threaded impaction hole, toconnect the component into the electric circuit 119. The component 105need not be specially modified for incorporation into the surfacetreatment apparatus 101. The surface treatment apparatus 101 maycomprise a number of different anode connectors, each specificallydesigned to connect to different components 105. In a similar manner,the surface treatment apparatus 101 may comprise a number of cathodeconnectors each configured to connect to differently shaped conductiveelements 117.

The voltage required may range from approximately 1 to 300 V, althoughtypically may be in the range of approximately 50 to 70 V. A highervoltage may be required in order to grow a thicker anodised layer on thesurface portion 103. The resultant coloured appearance of the surfaceportion 103 is dependent on the thickness of the metal oxide, and hencethe applied voltage. The coloured appearance results from theinterference of reflecting off the metal oxide surface and theunderlying metal surface.

The applied current may be a direct current (DC) or an alternatingcurrent (AC). The magnitude of the applied current may be selecteddepending on the surface area of the surface portion 103. The appliedcurrent density may typically range from approximately 30 to 300amperes/meter² (A/m²). As the surface portion 103 becomes anodised andthe metal oxide layer increases in thickness, the resistance of theelectric circuit 119 increases, thus reducing the current drawn from thepower supply. At the point that the electric current reachesapproximately zero amperes, the component 105 may be removed from thesurface treatment apparatus 101.

In the example of FIGS. 1a and 1 b, the surface treatment apparatus 101is configured to treat the rim of the acetabular cup. As such, theconductive element 117 comprises a metallic plate comprising a planarsurface 118 of similar form to the surface portion 103 of the rim of theacetabular cup. The conformable wicking element 107 is conformable toand covers the planar upper surface of the conductive element 117 suchthat it is not possible to expose the rim of the acetabular cup to theconductive element 117.

In an alternative example, the surface treatment apparatus 101 may beconfigured to treat one or more at least partially curved surfaces of acomponent 105. The conductive element 117 may comprise correspondinglyshaped surfaces that match the form of the one or more curved surfacesof a component 105. For example, the component 105 may comprise one ormore convex surfaces and the conductive element 117 may comprisecorresponding concave surfaces configured to receive the one or morecurved convex surfaces of the component 105. The conformable wickingelement 107 may be configured to conform to the convex surfaces and/orthe concave surfaces such that the conformable wicking element 107 is atleast partially disposed in between and in contact with the component105 and the conductive element 117. In another alternative example, theconformable wicking element 107 may be configured to extend across anopening in the conductive element 117 such that the conformable wickingelement 107 at least partially supports the component 105 over theopening in the conductive element 117.

In the example of FIGS. 1a and 1b the conductive element 117 issubmerged in the fluid 113 and is configured to support the conformablewicking element 107 such that the component 105 is supported above thesurface of the fluid. 113. In another example, the conformable wickingelement 107 may comprise one or more raised surface features configuredto support the component 105 above the surface of the fluid 113. In thismanner, the conformable wicking element 107 may be configured to drawthe fluid 113 directly from the fluid reservoir 111 and support and/orseparate the component from the fluid 113. In another example, theconformable wicking element 107 may support the component 105 above thesurface of the fluid 113 and may be remote from the conductive element117.

In one example of the present disclosure, the conductive element 117 maycomprise one or more grooves and/or recesses running at least partiallyacross a surface of the conductive element 117. In the example of FIGS.1a and 1 b, the grooves may be disposed in the upper surface 118 of theconductive element 117 that supports the conformable wicking element107. The grooves may be configured to allow the fluid 113 to flow acrossthe upper surface 118 of the conductive element 117. The grooves of theconductive plate 117 may act to drain excess fluid 113 away from theinterface between the conductive element 117 and the conformable wickingelement 107. The grooves may be configured to supply the conformablewicking element 107 with the minimum required amount of fluid 113 toavoid the conformable wicking element 107 becoming saturated. In oneexample, the grooves may form a grid pattern across the upper surface118 of the conductive element 117. The conformable wicking element 107may comprise one or more projections that extend into the grooves andbeneath the surface of the fluid 113. In this manner, the upper surface118 of the conductive element 117 may be disposed above the surface ofthe fluid 113 with the base of the grooves being disposed below thesurface of the fluid 113.

In a further example of the present disclosure, the surface treatmentapparatus 101 may comprise a rotational drive and/or an actuator, forexample a linear actuator, configured to rotate and/or move thecomponent 105 relative to the conformable wicking element 107. Rotationand translation movements of the component 105 are represented by arrow121 and arrow 123 respectively in FIG. 1 b. In some examples, movementof the component 105 relative to the conformable wicking element 107 mayresult in a more uniform anodised layer by preventing the contact regionbetween the conformable wicking element 107 and the surface portion 103from drying out. If the conformable wicking element 107 were to becometoo dry, the component 105 may become damaged as a result of sparkingbetween the component 105 and the conductive element 117.

In another example of the present disclosure, the surface treatmentapparatus 101 may comprise a vibrating device configured to vibrate thesurface treatment apparatus 101 and/or the component 105. In oneexample, the vibrating device may be configured to vibrate theconductive element 117. It may be advantageous to vibrate the surfacetreatment apparatus 101 and/or the component 105 during the anodisationprocess as vibrations may aid the conformable wicking element 107 absorbthe fluid 113 and may mitigate the conformable wicking element 107drying out during the anodisation process.

In another example of the present disclosure, the surface treatmentapparatus 101 may comprise a loading device configured to adjust thecontact pressure between the component 105 and the conformable wickingelement 107, as indicated by arrow 125 in FIG. 1 b. The loading devicemay be used to increase the contact pressure to ensure that theconformable wicking element 107 conforms to the shape of the surfaceportion 103 such that the surface portion 103 is sufficiently exposed tothe fluid 113.

In another example of the present disclosure, the surface treatmentapparatus 101 may comprise a sprayer configured to spray the fluid 113directly on to the conformable wicking element 107. In this manner, theconformable wicking element 107 need not be partially submerged withinthe fluid 113 in the fluid reservoir 111, and the conductive element 117may be configured to support the conformable wicking element 107 abovethe level of the fluid 113 in the fluid reservoir 111. The conformablewicking element 107 may be primed with the fluid 113 from the sprayerinstead of from the reservoir 111.

In another example of the present disclosure, the surface treatmentapparatus 101 may comprise a pump configured to pump the fluid 113. Inone example, the conductive element 117 may comprise one or morechannels extending through the conductive element 117. The channels maybe configured to connect the pump fluidically to the interface between asurface, e.g., the upper surface 118, of the conductive element 117 andthe conformable wicking element 107. The pump may be used to pump thefluid 113 through channels in order to supply the fluid 113 to and/ordrain the fluid 113 from the interface between the upper surface 118 ofthe conductive element 117 and the conformable wicking element 107. Thepump may be used to pump the fluid 113 from the fluid reservoir 111 tothe sprayer for the purpose of priming the conformable wicking element107.

In another example of the present disclosure, the surface treatmentapparatus 101 may comprise a controller. The controller may beconfigured to control the electric current supply. The controller may beused to modulate an AC supply applied between the component 105 and theconductive element 117. The controller may be used to monitor theelectrical resistance of the electric circuit 119 to determine thethickness of the anodised layer. The controller may be configured toautomatically adjust the current depending on the electrical resistanceof the electric circuit 119. The controller may be configured to controlone or more of: the rotational drive; the actuator; the vibratingdevice; the loading device; and the pump.

The present disclosure provides a method of selectively anodizing atleast the portion 103 of a surface of a component 105 using theanodising apparatus 101. The method comprises priming the conformablewicking element 107 with the fluid 113. The fluid may be drawn directlyfrom the fluid reservoir 111 or applied by any other appropriate method,for example spraying the fluid 113 on to the conformable wicking element107 and/or dipping the conformable wicking element 107 in the fluid 113prior to assembly onto the conductive element 117. The method furthercomprises bringing the component 105, for example the surface portion103, into contact with the conformable wicking element 107 in order tocomplete the electric circuit 119 between the conductive element 117 andthe component 105. The electric current is then applied between theconductive element 117 and the component 105 to grow the anodised layeron the portion 103 of the surface of the component that is in contactwith the conformable wicking element 107.

FIG. 2 shows another embodiment of the surface treatment apparatus 201for selectively treating, e.g. cleaning apparatus for selectivelycleaning, at least a portion 203 of a surface of a component 205according to the present disclosure.

In the embodiment of FIG. 2, the surface treatment apparatus 201comprises the conformable wicking element 207 and a second wickingelement 209 disposed in the fluid reservoir 211 containing the fluid213. The conformable wicking element 207 and the second wicking element211 are configured to absorb the fluid 213, for example by virtue ofcapillary action. The wicking element 207 and/or the second wickingelement 211 may be fabricated from a porous material. The pore size ofthe porous material from which the conformable wicking element 207and/or the second wicking element 209 is fabricated from may be selecteddepending on the desired rate of absorption of the fluid 213. Theconformable wicking element 207 and/or the second wicking element 211may be fabricated from different porous materials.

In the illustrated embodiment, the second wicking element 209 ispartially submerged in the fluid 213 such that the second wickingelement 209 is able to draw the fluid 213 through the thickness of thesecond wicking element 209. The conformable wicking element 207 is incontact with the second wicking element 211 such that the conformablewicking element 207 is able to draw the fluid 213 from the secondwicking element 209. In this manner, the conformable wicking element 207is primed with the fluid 211

The conformable wicking element 207 is conformable to at least the saidportion 203 of the surface of the component 205 such that, upon bringingthe component 205 into contact with the conformable wicking element 207,only the said portion 203 of the surface of the component 205 is exposedto the fluid 213. FIG. 2 shows the component 205, for example anacetabular cup, in contact with the conformable wicking element 207. Inthe embodiment of FIG. 2 only the rim of the acetabular cup is incontact with the conformable wicking element 207. In this manner, thesurface treatment apparatus 201 is configured to clean only a selectedsurface of component 205.

In the embodiment of FIG. 2, the fluid 213 comprises a cleaning fluid,for example an acid or any other appropriate fluid configured to cleanthe said portion 203 of the surface of the component 205. For theexample of a metallic component, e.g. a titanium acetabular cup, thecleaning fluid may be configured to remove a metal oxide layer from thesaid portion 203.

The surface treatment apparatus 201 shown in the embodiment in FIG. 2may be used to selectively clean the said portion 203 of the surface ofthe component 205 prior to the said portion 203 undergoing a furthersurface treatment process. In one example of the present disclosure, thesurface treatment apparatus 201 may be used to selectively clean thesaid portion 103, 203 of the component 105, 205 prior to the surfacetreatment apparatus 101 being used to selectively anodise the saidportion 103, 203 of the component 105, 205. However, in an alternativeexample, the surface treatment apparatus 201 may be used subsequent toanother surface treatment process.

1. An anodising apparatus for selectively anodizing at least a portionof a surface of a component, the anodising apparatus comprising: aconformable wicking element configured to absorb a fluid, theconformable wicking element being conformable to at least the saidportion of the surface of the component, wherein, upon bringing thecomponent into contact with the conformable wicking element, the fluidcompletes an electric circuit between the component and a conductiveelement, the anodising apparatus being configured to grow an anodisedlayer on the said portion of the surface of the component that is incontact with the conformable wicking element when an electric current issupplied to the electric circuit between the conductive element and thecomponent.
 2. The anodising apparatus according to claim 1, wherein thefluid is exposed only to the said portion of the surface of thecomponent upon bringing the component into contact with the conformablewicking element.
 3. The anodising apparatus according to claim 1,wherein the conformable wicking element is configured to draw the fluidfrom a reservoir of fluid.
 4. The anodising apparatus according to claim3, wherein the conformable wicking element is at least partiallysubmerged in the fluid.
 5. The anodising apparatus according to claim 1,wherein the conformable wicking element comprises a sheet of porousmaterial.
 6. The anodising apparatus according to claim 1, wherein theconformable wicking element is in contact with the conductive elementand the said portion of the surface of the component.
 7. The anodisingapparatus according to claim 1, wherein the conformable wicking elementis configured to at least partially cover one or more surfaces of theconductive element.
 8. The anodising apparatus according to claim 1,wherein the conformable wicking element is at least partially disposedin between the component and the conductive element.
 9. The anodisingapparatus according to claim 1, wherein the conformable wicking elementis conformable to at least a portion of a surface of the conductiveelement.
 10. The anodising apparatus according to claim 1, wherein theconductive element comprises a planar surface at least partially incontact with the conformable wicking element.
 11. The anodisingapparatus according to claim 10, wherein the conductive element isconfigured to support the conformable wicking element.
 12. The anodisingapparatus according to claim 1, wherein the conductive element comprisesa metallic plate.
 13. The anodising apparatus according to claim 1,wherein the conductive element comprises one or more grooves running atleast partially across a surface of the conductive element, the groovesbeing configured to allow the fluid to flow across the said surface ofthe conductive element.
 14. The anodising apparatus according to claim13, wherein the grooves extend at least partially across the surface ofthe conductive element from the periphery of the conductive element. 15.The anodising apparatus according to claim 14, wherein the grooves forma grid pattern on the surface of the conductive element.
 16. Theanodising apparatus according to claim 15, wherein the grooves areconfigured to drain fluid away from the conformable wicking element. 17.The anodising apparatus according to claim 1, wherein the conductiveelement comprises a porous conductive material configured to absorb thefluid.
 18. The anodising apparatus according to claim 1, wherein theconductive element comprises a first layer of a non-porous conductivematerial and a second layer of porous conductive material configured toabsorb the fluid.
 19. The anodising apparatus according to claim 1,further comprising a second wicking element configured to absorb thefluid, the second wicking element being in contact with the conformablewicking element, the conformable wicking element being configured todraw the fluid from the second wicking element.
 20. The anodisingapparatus according to claim 1, wherein the conductive element forms acathode of the anodising apparatus, and wherein the component forms ananode of the anodising apparatus.
 21. The anodising apparatus accordingto claim 1, further comprising a rotational drive configured to rotatethe component.
 22. The anodising apparatus according to claim 1, furthercomprising a vibrating device configured to vibrate the component. 23.The anodising apparatus according to claim 1, further comprising aloading device configured to adjust the contact pressure between thecomponent and the conformable wicking element.
 24. The anodisingapparatus according to claim 1, wherein the component is a prosthesis.25. The anodising apparatus according to claim 1, wherein the fluidcomprises an electrolyte fluid.